Add PatientUpdateFromPDSJob

This adds a new job which handles updating patient information from PDS
in the background, for patients where we already have their NHS number
so we don't need to perform a search for the patient first.

app/jobs/patient_update_from_pds_job.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class PatientUpdateFromPDSJob < ApplicationJob
+  include NHSAPIConcurrencyConcern
+
+  queue_as :patients
+
+  def perform(patient)
+    raise MissingNHSNumber if patient.nhs_number.nil?
+
+    pds_patient = NHS::PDS.get_patient(patient.nhs_number).body
+    patient.update_from_pds!(pds_patient)
+  end
+
+  class MissingNHSNumber < StandardError
+  end
+end

spec/jobs/patient_update_from_pds_job_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+describe PatientUpdateFromPDSJob do
+  subject(:perform_now) { described_class.perform_now(patient) }
+
+  context "without an NHS number" do
+    let(:patient) { create(:patient, nhs_number: nil) }
+
+    it "raises an error" do
+      expect { perform_now }.to raise_error(
+        PatientUpdateFromPDSJob::MissingNHSNumber
+      )
+    end
+  end
+
+  context "with an NHS number" do
+    before do
+      stub_request(
+        :get,
+        "https://sandbox.api.service.nhs.uk/personal-demographics/FHIR/R4/Patient/0123456789"
+      ).to_return(
+        body: file_fixture("pds/get-patient-response.json"),
+        headers: {
+          "Content-Type" => "application/fhir+json"
+        }
+      )
+    end
+
+    let(:patient) { create(:patient, nhs_number: "0123456789") }
+
+    it "updates the patient details from PDS" do
+      expect(patient).to receive(:update_from_pds!)
+      perform_now
+    end
+  end
+end